Answer:
Increasing atomic number - True
Explanation:
The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass.
The Atomic number is the number of protons in an atom, and this number is unique for each element. For example, Hydrogen has an atomic number of 1, Calcium has an atomic number of 20.
In the modern periodic table the elements are further arranged into:
- rows, called periods, in order of increasing atomic number. Elements in the same periods have the same number of shells.
- vertical columns, called groups, where the elements have similar properties. Elements in the same group has the same number of valency (outermost number of electrons)
Answer:
Explanation:
We need to use the formula for heat of vaporization.
Identify the variables.
- The heat absorbed by the evaporating water is the <u>latent heat of vaporization. </u>For water, that is 2260 Joules per gram.
- Q is the energy, in this problem, 50,000 Joules.
- m is the mass, which is unknown.
Substitute the values into the formula.
We want to find the mass. We must isolate the variable, m.
m is being multiplied by 2260 J/g. The inverse operation of multiplication is division. Divide both sides by 2260 J/g.
Divide. Note that the Joules (J) will cancel each other out.
Round to the nearest whole number. The 1 in the tenth place tells us to leave the number as is.
The mass is about 22 grams, so choice B is correct.
Answer:
what is the formula of rectangle
STP means standard temperature and pressure which is equivalent to 273 K and 1 atm, respectively. Assuming ideal gas behavior, the solution for this problem is as follows:
PV = nRT
Solve for n,
n = RT/PV
n = (0.0821 L-atm/mol-K)(273 K)/(1 atm)(1×10⁵ L)
<em>n = 2.24×10⁻⁴ moles</em>
Answer:
The law of definite proportions
Explanation:
The law of definite proportions states that atoms combine in a molecule in a specific molar ratio or specific stoichiometry. For example, it's proved that regardless of the quantity we take, two hydrogen atoms always combine with one oxygen atom to form a water molecule.
Similarly, ionic substances follow the same pattern. Since the net charge of ionic salts should be equal to 0 and each element has a definite number of valence electrons in its shell all the time, the ions combine in a way, so that cations balance the charge of anions.
Essentially, the law of definite proportions is applicable and will be applicable in the future, since we know that each element has a fixed number of valence electrons in its ground state.
